EAP225-Wall LAN ports cannot do VLAN. You may consider your client device connects to this LAN port work like it connects to the switch directly. So we need to do settings on the switch, set up Profile(one the Network settings) that VLAN 4 untag. However, with these settings your EAP SSID can not use VLAN 4 anymore. It's a hardware limitation I don't know if tplink can improve it

  @Somnus 

Right?

But if i switch the EAP to a e.g. VLAN4 Port, does than works all WiFi' s on this EAP Wall?

Think then only the WiFi works, whitch is configurated for VLAN4, or?